1. Field of the Invention
The present invention relates to a method and apparatus for separating two immiscible substances, such as removing waste oil particles from a waste water stream of brine solution, and more particularly relates to an improved method of removing relatively small waste oil particles, for instance than with having a particle size in the range of less than 150 microns in diameter from a waste water stream of brine wherein seed oil particles are transmitted to the waste water stream from an external source and allowing the seed oil particles and the waste oil particles to comingle in the waste water stream for a time interval sufficiently long so that the waste oil particles combine with the seed oil particles prior to a removal of the oil using an oil/water separator.
2. General Background
Waste water streams commonly include as a pollutant, suspended oil particles, many of which are in the very small range of less than 150 microns in diameter. The separation of these very small oil particles can be quite difficult using common oil/water separators. Many times the waste water streams contain other components, such as brine, solids, gases, and dissolved hydrocarbons.
Several systems have been proposed for the separation of oil from a waste water stream.
U.S. Pat. No. 1,383,479, issued to W. W. Nugent, entitled "Combined Filter And Water Separator," relates to an apparatus for removing impurities from lubricating oil and also for separating water from lubricating oil, and the principal object of this invention is to provide an improved device of this nature which is made up of detachable sections to facilitate transportation and the assembly thereof at the place of use.
U.S. Pat. No. 2,656,508, issued to W. H. Coulter, and entitled "Means For Counting Particles Suspended In A Fluid," discloses a Coulter Counter device. The '508 patent relates to means for detecting and counting particles suspended in a fluid medium. The principal object of this invention is to provide a means for detecting and counting particles suspended in a fluid with a greater accuracy, more quickly, and economically. The apparatus consists of reducing the dimensions of or constricting an electric current path in a fluid so that the presence or controlled movement of the article bearing fluid in, through, or past such path will, by reason of the difference in conductivity between the fluid and the particles, cause the individual particles to modulate the current in a detectable manner.
U.S. Pat. No. 2,730,190, issued to J. S. Brown et al., entitled "Treatment Of Oil-Containing Water," relates to the purification of contaminated water and in particular relates to the removal and recovery of oils of various types from oil-contaminated water.
U.S. Pat. No. 3,233,173, issued to S. Lees et al., entitled "Method Of Determining The Volume Of Particles In A Mixture," relates to indicating devices and more particularly comprises a method of detecting moving particles in a medium. The '173 Lees patent provides a detection system which may control an alarm or signaling device to indicate excessive amounts of contaminants in a fuel line. Another object provides a method for detecting changes in the electromagnetic properties of a material passing through a duct.
U.S. Pat. No. 3,399,135, issued to W. R. Conley, Jr., et al., entitled "Method Of Removing Solids From Liquids," provides a method for liquid carrying solids is passed at slow rate through honeycomb of tubes of restricted diameter to permit solids to deposit within tubes. Restricted diameter of the tubes causes self orificing to utilize complete storage capacity of tubes. Tubes are cleaned by draining inlet plenum, and the tubes being inclined upwardly from such plenum.
U.S. Pat. No. 3,469,702, issued to B. Perren, entitled "Apparatus For Separating Fluid Earth-Oil Products From An Earth-Oil-In-Water Mixture," is an apparatus for the separation of liquid petroleum products from a mixture of such products and water and comprising a container having a material contactable by the liquid having a higher wetting ability or affinity than water. The apparatus has separate outlets for the water freed from the petroleum products and the separated petroleum products.
U.S. Pat. No. 3,945,918, issued to B. S. Kirk, entitled "Methods And Apparatus For Treating A Liquid With A Gas," provides a method and apparatus for treating a liquid with a gas wherein a liquid feed is introduced to the initial stage of a multi-stage device for dissolving the gas in the liquid. Efficient mass transfer is achieved by effecting a gas-liquid counter flow in serial stages of the dissolution device. The effluent from the dissolution device exhibits a relatively high dissolved gas concentration which gas is subsequently consumed by the liquid in a reaction tank. A liquid recycle line is provided for returning and combining treated liquid with the incoming feed thereby enabling further dissolution of the gas in the liquid. In the course of treating wastewater with ozone, a flotation clarifier may be provided with the initial stage of the dissolution device to enable the surface coagulation of impurities in the wastewater feed. The coagulants may be skimmed prior to introducing wastewater into subsequent stages of the dissolution device, thereby substantially reducing the ultimate ozone demand of the wastewater.
U.S. Pat. No. 4,137,494, issued to F. Malley et al., entitled "Apparatus And Method For Analyzing Oil Content Of Water," discloses an oil content analyzer device containing a degradable ion transport cell designed to present a changing internal impedance as a function of the oil content of water flowing therethrough. The cell is comprised of two electrodes made of dissimilar metallic compositions with a hydrocarbon-absorbing material sandwiched therebetween, and housed in a container having openings to permit water flow therethrough. In operation, a sample of water is circulated through the degradable ion transport generating device with the result that the electrical output characteristics of the device change as a function of the amount of hydrocarbons absorbed in the membrane element, whereby an electrical signal is generated which is inversely proportional to the oil content of the analyzed water sample.
U.S. Pat. No. 4,172,789, issued to J. Huardeau, entitled "Process For Clarifying Liquids Loaded With Solid Substances In Suspension," provides a process and apparatus for clarifying a liquid loaded with suspended solid substances by decanting said substances, wherein the liquid to be treated is caused to flow along a flow path at least one portion of which is an upwardly directed flow path portion having a geometrical axis inclined with respect to the horizontal, said flow path portion being defined within an enclosure in which said liquid flows between plates arranged in at least two groups, each group containing substantially equidistant positioned plates disposed parallel to said inclined axis, said plates of each one of said groups being parallel to each other, and the parallel plates of each group forming with the vertical plane comprising said inclined axis an angle different from 90 degrees, while forming with the plates of the other group an angle of between about 20 degrees and 75 degrees, whereby the suspended substances are deposited on said plates and then slide downwardly thereon toward the wall of said enclosure.
U.S. Pat. No. 4,390,842, issued to N. D. Wygant et al., entitled "Fluid Conductivity Device For Measuring Fluid Volumes And Method Therefor," provides a device and method for measuring the volumes of oil and water in an oil and water mixture wherein the mixture flows at a constant volumetric flow rate. The device includes a formed cylindrical passageway capable of receiving the fluid mixture and for separating the fluid mixture into separate oil and water droplets while maintaining the constant volumetric flow rate. Electrical probes mounted across the passageway are interconnected with an alternating current source to apply current to the flowing oil and water droplets in the passageway. The resulting sinusoidal voltage pulses produced by the flowing oil and water droplets are compared to a predetermined voltage level and if a water droplet passes the probes, the sinusoidal voltage pulses exceed the predetermined level and these pulses are then counted. If the sinusoidal electrical pulses are less than the predetermined level due to the low conductivity of the oil droplet, then no output pulses are generated and the counter remains inactive. The pulse information provided provides a time difference between the leading and lagging interfaces of each droplet between the oil droplets and the water droplets and the measured time difference is proportional to the volume of the droplets.